Compasses for drawing oviform curves



J. HARDT. COMPASSES FOR DRAWING OVIFORM CURVES.

APPLICATION FILED AUG.5, I92].

Patented Oct. 10, 1922..

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, wApplicationifiled August 5, 1921. seriaino. 490,127.

sists in the fact that the compass has three points adapted to be adjusted with regard to one another, a string attached to one of the points being placed around the other points. When a pencil is moved along the inner side of said string so that the string is stretched outward the oviformcurve is produced.

In order that the invention may be clearly understood, I shall proceed to describe the same with reference to the formof construe tion shown byway of example in the ac companying drawing, wherein Fig. 1 is a perspective view showing the compass in use.

Fig. 2 illustrates how is formed. 1

The shank 1 of a two-shanked compass has in its point 2 an eye througlrwhich the ends 3 and 4: of a string are passed. The ends 3 and 4t ofthe string are then attached to a sleeve 5 which is adjustably mounted on the shank 1 of the compass. A screw 6 serves for fixing the sleeve 5 i in its adjusted position. The string forms a loop at the point 2 of the shank the diameter of said loopbeing varied by the adjustment of the sleeve 5.

the oviform curve A. sleeve 8 is adjustably mounted on thesecond shank 7 of the compass to be fixed in position bya screw 9.. The sleeve 8 has two eyes 10 in which the arms 11, 11 are pivotedwhich are hingedly connected with the lower end 13 of shank 7 by means of articulated pieces 12, 12. The arms 11, 11 terminate in the points 15, 15 and have projections 14, 14: (designed toguide the string.

The compass is mounted upon the surface on which the curve has to be drawn so that its point 2 is situated on the middle line of the curve, the points 15,15 of the compass line. The distance between the points 15,

15 is regulated by the adjustment of sleeve 8 upon the shank 7. i j

formed by the string.

and if the pencil is conducted along the inner side 01 the string an oviform curve is drawn which is composed of three elliptic curves.

When the point 2 of the compass is mounted at point a (Fig. 2), the points 15, 15 being mounted in the points I), c (Fig. 2), the length of the string which is in contact with the points at a, b, 0 is not altered between the points a, c and b, 0 so that the pencil describes half an ellipse with the middle line 03, (Z between two points 20 and 21. When the pencil 16 is moved further the string is fixed between the points a, b and a, 0 and the pencil describes an elliptic curve 21, 23 with regard to the middle line 7, 7. The string is finally fixed at the points a, I) and b, c and the pencil describes the half ellipse 23, 22 to the ellipse middle line 0, c.

Any desired shape of an oviform curve can be obtainedby varying correspondingly the position of the points 15, 15 the one with gard to the points 15, 15 and that of sleeve 5 upon the shank 1.

I claim 1. A compass for the drawing of oviform curves comprising in combination a single point and two points arranged in pair, and adjustably connected to each other, a string adjustably attached with its ends to the single point and placed in a loop around the points arranged in pair sothat when said string is beingstretched by means of a pencil moved along the inner side of said string the two points arranged in pair act successively as contact points for the string.

2. A compass for the drawing of oviform curves comprising in combination a shank having a point provided with an eye, a sleeve adjustably mounted upon said shank, means for fixing said sleeve in adjusted position, two eyes of said sleeve, a second shank ,without point, a sleeve adjustably mounted on said pointless shank, means for securing said sleeve in adjusted position thereon, two pointed arms hinged to said sleeve, articulated pieces connecting said arms with the end of said pointless shank,

projections on the front side of said arms in a pencil moved along the inner side of the 10 proximity With the pointed enCs of said string an oviform curve is drawn by said arms, and a string attached With its ends to pencil.

the eyes o1 the sleeve of the pointed shank In testimony whereof I nflix my signaafter they have been passed through the eye ture in presence of two witnesses.

of the point so that the string forms a loop, JOHANN HARDT. the string being in contact with the outer -W'itnesses: surfaces of said pointed arms so that when FRIEDRICH KEIL,

said string is being stretched by means of MARGARETE TEILL. 

